A generic filter apparatus is known, e.g., from WO 01/80971 A1. Non-clarified liquid is present in a container and is clarified by filter elements of a filter apparatus. The clarified liquid is supplied as permeate via a conduit system of a hollow shaft. The transfer of the permeate from the hollow shaft into a stationary pipeline by which the permeate is transported out of the container takes place in a swivel joint bearing that is supposed to seal the permeate line relative to the non-clarified liquid. This has the disadvantage that when the seals fail, non-clarified liquid can pass into the permeate and thus the already clarified liquid is contaminated again. This results in significant adverse effects on the purification of the wastewater.
The present invention ensures that the penetration of wastewater into the permeate is reliably prevented.